Fast reboot & Disk fragmentation

[PB Schechter]

I have a couple of questions that I have seen discussed in the past but
have not (of course) kept track of, and so am reduced to asking them
again.

First, I seem to remember that someone made a simple modification
(somewhere) so that when shutting the system down normally, a key word
is written to a key file, so that, upon subsequent rebooting, fsck need
not be run (greatly speeding up the reboot process).  Rather than
create this myself, I am hoping that someone will mail (or post, if you
think there is sufficient interest) what they did to me.

Second, my disk is getting to the 60-70% full range, and things are
starting to slow down.  Are there any suggestions for defragmentation?
I know that I can copy everything to tape, delete it from my disk, and
copy it back.  However, I'm looking for something easier, if it exists.
(I seem to remember reports of a "defragmentation program" that someone
has run, for example.)

Thanks in advance for any suggestions.

PB Schechter
pb at cs.wisc.edu